[LEAPSECS] Lets get REAL about time.

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Jan 20 11:34:12 EST 2012

In message <4F19885C.3090502 at sfr.fr>, mike cook writes:

>> Modern CPUs clock around 4GHz, multiplying by 1000 for resulution we

>> find that we need 42 bits after the binary point.


>Solaris already has 64 bit quantities for time operations. From their doc:


>"time_t, and its derivative types struct timeval and timespec_t now =


>contain 64-bit quantities"


>Aren't you reinventing the wheel? Its open source, so just borrow it.

No, time_t is entirely in front of the binary point: It counts seconds.

We need something which will also do the fractions of seconds and without
braindamage of the "struct timeval" type.

>> Our new timecale should run on the TAI timescale which does not

>> have leap-seconds or any other artifacts, and library functions can

>> convert that to UTC time, civil time etc, using a leap-second table

>> which can be updated as and when leap-seconds gets announced.


>Fine, but if TAI is going to be adopted anytime as the standard of time =

>dissemination, nobody is going to be announcing leap seconds, UNLESS, =

>parallel time scales spring up.

PTP already uses TAI

TAI can be derived from UTC, GPS and other broadcast timescales, so
availability is fine.

Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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